U.S. patent number 10,761,442 [Application Number 16/430,860] was granted by the patent office on 2020-09-01 for electrophotographic photosensitive member, electrophotographic apparatus, process cartridge, and method of producing electrophotographic photosensitive member.
This patent grant is currently assigned to CANON KABUSHIKI KAISHA. The grantee listed for this patent is CANON KABUSHIKI KAISHA. Invention is credited to Ryuji Higashi, Yuto Ito, Isao Kawata, Shubun Kujirai, Haruki Mori, Koichi Nakata, Shinji Takagi.
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United States Patent |
10,761,442 |
Nakata , et al. |
September 1, 2020 |
Electrophotographic photosensitive member, electrophotographic
apparatus, process cartridge, and method of producing
electrophotographic photosensitive member
Abstract
Provided are an electrophotographic photosensitive member
including a support and a photosensitive layer above the support,
in which a surface layer of the electrophotographic photosensitive
member includes a polymerization product of a composition
containing a specific hole transporting compound, and an
electrophotographic apparatus and a process cartridge including the
electrophotographic photosensitive member. Also provided is a
method of producing the electrophotographic photosensitive member,
including (i) forming a coating film of a coating solution for a
surface layer which is a composition containing a specific hole
transporting compound, and (ii) forming the surface layer of the
electrophotographic photosensitive member by a polymerization
reaction of the composition containing the specific hole
transporting compound.
Inventors: |
Nakata; Koichi (Tokyo,
JP), Mori; Haruki (Ichikawa, JP), Kujirai;
Shubun (Toride, JP), Takagi; Shinji (Yokohama,
JP), Kawata; Isao (Kawasaki, JP), Ito;
Yuto (Koganei, JP), Higashi; Ryuji (Kawasaki,
JP) |
Applicant: |
Name |
City |
State |
Country |
Type |
CANON KABUSHIKI KAISHA |
Tokyo |
N/A |
JP |
|
|
Assignee: |
CANON KABUSHIKI KAISHA (Tokyo,
JP)
|
Family
ID: |
66821041 |
Appl.
No.: |
16/430,860 |
Filed: |
June 4, 2019 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20190391504 A1 |
Dec 26, 2019 |
|
Foreign Application Priority Data
|
|
|
|
|
Jun 22, 2018 [JP] |
|
|
2018-118897 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G03G
5/0592 (20130101); G03G 5/14791 (20130101); G03G
5/0596 (20130101); G03G 5/14786 (20130101); G03G
5/0589 (20130101); G03G 5/14717 (20130101); G03G
5/14734 (20130101); G03G 5/071 (20130101); G03G
5/14795 (20130101); G03G 5/0607 (20130101); G03G
5/076 (20130101); G03G 5/0614 (20130101) |
Current International
Class: |
G03G
5/07 (20060101); G03G 5/147 (20060101) |
Field of
Search: |
;430/58.7,66 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
2 527 923 |
|
Nov 2012 |
|
EP |
|
05173350 |
|
Jul 1993 |
|
JP |
|
09325509 |
|
Dec 1997 |
|
JP |
|
2007-011005 |
|
Jan 2007 |
|
JP |
|
2007-011006 |
|
Jan 2007 |
|
JP |
|
2007-272191 |
|
Oct 2007 |
|
JP |
|
2007-272192 |
|
Oct 2007 |
|
JP |
|
2007-279678 |
|
Oct 2007 |
|
JP |
|
2008-070761 |
|
Mar 2008 |
|
JP |
|
2016-051030 |
|
Apr 2016 |
|
JP |
|
2016-161699 |
|
Sep 2016 |
|
JP |
|
Other References
US. Appl. No. 16/416,929, Haruki Mori, filed May 20, 2019. cited by
applicant .
U.S. Appl. No. 16/423,337, Yuka Ishiduka, filed May 28, 2019. cited
by applicant .
U.S. Appl. No. 16/423,418, Hiroyuki Watanabe, filed May 28, 2019.
cited by applicant .
U.S. Appl. No. 16/423,429, Nobuhiro Nakamura, filed May 28, 2019.
cited by applicant.
|
Primary Examiner: Rodee; Christopher D
Attorney, Agent or Firm: Venable LLP
Claims
What is claimed is:
1. An electrophotographic photosensitive member, comprising: a
support; a photosensitive layer above the support; and a surface
layer that includes a copolymerization product of a composition
containing a hole transporting compound represented by Formula (1)
and a compound represented by Formula (2): ##STR00024## where
R.sup.1 and R.sup.2 independently represent an alkyl group having 2
to 8 carbon atoms, R.sup.3 and R.sup.4 independently represent a
hydrogen atom or an alkyl group having 4 or less carbon atoms,
R.sup.11 and R.sup.13 independently represent an alkylene group
having 3 to 6 carbon atoms, and R.sup.12 and R.sup.14 independently
represent a hydrogen atom or a methyl group, and ##STR00025## where
R.sup.21 and R.sup.22 independently represent an alkyl group having
1 to 4 carbon atoms, or a substituted or unsubstituted benzyl
group, the substituent of the benzyl group is an alkyl group having
4 or less carbon atoms, R.sup.21 and R.sup.22 may be bonded to each
other to form a ring, R.sup.23 represents an alkyl group having 1
to 4 carbon atoms, and R.sup.24 and R.sup.25 independently
represent a hydrogen atom or a methyl group.
2. The electrophotographic photosensitive member according to claim
1, where R.sup.1 and R.sup.2 are independently an alkyl group
having 2 to 5 carbon atoms, and R.sup.11 and R.sup.13 are each a
propylene group.
3. The electrophotographic photosensitive member according to claim
2, where R.sup.1 and R.sup.2 are each a propyl group.
4. The electrophotographic photosensitive member according to claim
1, where at least one of R.sup.21 and R.sup.22 is an alkyl group
having 2 or more carbon atoms.
5. An electrophotographic apparatus comprising: an
electrophotographic photosensitive member, a charging unit, an
exposing unit, a developing unit and a transfer unit, wherein the
electrophotographic photosensitive member includes a support, a
photosensitive layer above the support, and a surface layer that
includes a copolymerization product of a composition containing a
hole transporting compound represented by Formula (1) and a
compound represented by Formula (2): ##STR00026## where R.sup.1 and
R.sup.2 independently represent an alkyl group having 2 to 8 carbon
atoms, R.sup.3 and R.sup.4 independently represent a hydrogen atom
or an alkyl group having 4 or less carbon atoms, R.sup.11 and
R.sup.13 independently represent an alkylene group having 3 to 6
carbon atoms, and R.sup.12 and R.sup.14 independently represent a
hydrogen atom or a methyl group, and ##STR00027## where R.sup.21
and R.sup.22 independently represent an alkyl group having 1 to 4
carbon atoms, or a substituted or unsubstituted benzyl group, the
substituent of the benzyl group is an alkyl group having 4 or less
carbon atoms, R.sup.21 and R.sup.22 may be bonded to each other to
form a ring, R.sup.23 represents an alkyl group having 1 to 4
carbon atoms, and R.sup.24 and R.sup.25 independently represent a
hydrogen atom or a methyl group.
6. The electrophotographic apparatus according to claim 5, where at
least one of R.sup.21 and R.sup.22 is an alkyl group having 2 or
more carbon atoms.
7. A process cartridge which integrally supports an
electrophotographic photosensitive member and at least one unit
selected from the group consisting of a charging unit, a developing
unit, a transfer unit and a cleaning unit, and is detachably
attachable to an electrophotographic apparatus main body, wherein
the electrophotographic photosensitive member includes a support, a
photosensitive layer above the support, and a surface layer that
includes a copolymerization product of a composition containing a
hole transporting compound represented by Formula (1) and a
compound represented by Formula (2): ##STR00028## where R.sup.1 and
R.sup.2 independently represent an alkyl group having 2 to 8 carbon
atoms, R.sup.3 and R.sup.4 independently represent a hydrogen atom
or an alkyl group having 4 or less carbon atoms, R.sup.11 and
R.sup.13 independently represent an alkylene group having 3 to 6
carbon atoms, and R.sup.12 and R.sup.14 independently represent a
hydrogen atom or a methyl group, and ##STR00029## where R.sup.21
and R.sup.22 independently represent an alkyl group having 1 to 4
carbon atoms, or a substituted or unsubstituted benzyl group, the
substituent of the benzyl group is an alkyl group having 4 or less
carbon atoms, R.sup.21 and R.sup.22 may be bonded to each other to
form a ring, R.sup.23 represents an alkyl group having 1 to 4
carbon atoms, and R.sup.24 and R.sup.25 independently represent a
hydrogen atom or a methyl group.
8. The process cartridge according to claim 7, where at least one
of R.sup.21 and R.sup.22 is an alkyl group having 2 or more carbon
atoms.
9. A method of producing an electrophotographic photosensitive
member including a support and a photosensitive layer above the
support, the method comprising: (i) forming a coating film of a
coating solution composition for a surface layer of the
electrophotographic photosensitive member, said composition
containing a hole transporting compound represented by Formula (1)
and a compound represented by Formula (2): ##STR00030## where
R.sup.1 and R.sup.2 independently represent an alkyl group having 2
to 8 carbon atoms, R.sup.3 and R.sup.4 independently represent a
hydrogen atom or an alkyl group having 4 or less carbon atoms,
R.sup.11 and R.sup.13 independently represent an alkylene group
having 3 to 6 carbon atoms, and R.sup.12 and R.sup.14 independently
represent a hydrogen atom or a methyl group, and ##STR00031## where
R.sup.21 and R.sup.22 independently represent an alkyl group having
1 to 4 carbon atoms, or a substituted or unsubstituted benzyl
group, the substituent of the benzyl group is an alkyl group having
4 or less carbon atoms, R.sup.21 and R.sup.22 may be bonded to each
other to form a ring, R.sup.23 represents an alkyl group having 1
to 4 carbon atoms, and R.sup.24 and R.sup.25 independently
represent a hydrogen atom or a methyl group; and (ii) forming the
surface layer by a copolymerization reaction of the coating
solution composition in the coating film.
10. The method of producing an electrophotographic photosensitive
member according to claim 9, wherein a content of the hole
transporting compound represented by Formula (1) in the coating
solution composition for a surface layer is 50% by mass or more
with respect to a total mass of the hole transporting compound
represented by Formula (1) and the compound represented by Formula
(2) in the coating solution composition for a surface layer.
11. The method of producing an electrophotographic photosensitive
member according to claim 9, where at least one of R.sup.21 and
R.sup.22 is an alkyl group having 2 or more carbon atoms.
Description
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to an electrophotographic
photosensitive member, an electrophotographic apparatus having the
electrophotographic photosensitive member, a process cartridge
having the electrophotographic photosensitive member, and a method
of producing the electrophotographic photosensitive member.
Description of the Related Art
Since stress is repeatedly applied to a surface layer of an
electrophotographic photosensitive member (hereinafter, also
referred to as a photosensitive member) by a series of
electrophotographic processes such as charging, exposure,
development, transfer, and cleaning, wear resistance and chemical
stability are required.
As a method for improving wear resistance, a method of
incorporating a curable resin in the surface layer of the
electrophotographic photosensitive member can be used. However,
when a surface layer having high wear resistance is provided, the
surface layer is less likely to wear out, whereby removal along
with wear of a chemically deteriorated surface of the surface layer
does not proceed and chemical deterioration is likely to accumulate
on the surface. Chemical deterioration refers to a phenomenon in
which a hole transporting compound of the surface layer of the
photosensitive member causes a chemical change by the stress due to
the series of the above-mentioned electrophotographic processes.
The chemical change of the hole transporting compound sometimes
causes a phenomenon in which an electrophotographic image output
after repeated use under a high temperature and high humidity
environment becomes unclear (hereinafter, also referred to as
smeared image). Therefore, in order to suppress smeared image, it
is required to suppress the chemical change of the hole
transporting compound.
As a method to improve chemical stability of the hole transporting
compound, there is a technique to incorporate an additive together
with the hole transporting compound in the surface layer. Japanese
Patent Application Laid-Open No. 2007-11005 discloses a technique
to improve smeared image by adding a specific fluorine
atom-containing monomer having a polymerizable functional group to
a surface layer. Japanese Patent Application Laid-Open Nos.
2007-11006 and 2016-51030 disclose a technique to include a
specific fluorine atom-containing hole transporting monomer in the
surface layer. Japanese Patent Application Laid-Open Nos.
2007-272191, 2007-272192, and 2007-279678 disclose a technique to
improve smeared image by adding a specific amine compound to the
surface layer. Japanese Patent Application Laid-Open No. 2008-70761
discloses a technique to improve smeared image by adding a specific
siloxane compound having a specific polymerizable functional group
to a surface layer.
A technique using the compounds of Japanese Patent Application
Laid-Open Nos. 2007-11005, 2007-272191, 2007-272192, 2007-279678,
and 2008-70761 is a technique for alleviating the above-described
stress exposure to the hole transporting compound, but is not a
technique for improving chemical stability as the hole transporting
compound. In addition, Japanese Patent Application Laid-Open No.
2007-11006 discloses making the surface layer have low surface
energy, but discloses neither chemical deterioration of the surface
layer nor a potential fluctuation when used repeatedly under a low
humidity environment. The technique of Japanese Patent Application
Laid-Open No. 2016-51030 does not disclose suppression of a
potential fluctuation during repeated use under a low humidity
environment.
In order to improve smeared image, it is required not only to
alleviate the above-described stress exposure, but also to improve
chemical stability of the hole transporting compound itself. In
addition, it is also required to improve the potential fluctuation
when a highly durable photosensitive member is repeatedly used
under a low humidity environment.
SUMMARY OF THE INVENTION
Therefore, an embodiment of the present invention is to provide an
electrophotographic photosensitive member which has wear
resistance, suppresses smeared image under a high temperature and
high humidity environment, and also, has a small potential
fluctuation when repeatedly used under a low temperature and low
humidity environment.
Another embodiment of the present invention is to provide an
electrophotographic apparatus having the electrophotographic
photosensitive member.
Another embodiment of the present invention is to provide a process
cartridge having the electrophotographic photosensitive member.
Still another embodiment of the present invention is to provide a
method of producing the electrophotographic photosensitive
member.
The electrophotographic photosensitive member according to an
embodiment of the present invention is an electrophotographic
photosensitive member including a support and a photosensitive
layer above the support, in which a surface layer of the
electrophotographic photosensitive member includes a polymerization
product of a composition containing a hole transporting compound
represented by the following Formula (1):
##STR00001##
in Formula (1), R.sup.1 and R.sup.2 independently represent an
alkyl group having 2 or more and 8 or less carbon atoms, R.sup.3
and R.sup.4 independently represent a hydrogen atom or an alkyl
group having 4 or less carbon atoms, R.sup.11 and R.sup.13
independently represent an alkylene group having 3 or more and 6 or
less carbon atoms, and R.sup.12 and R.sup.14 independently
represent a hydrogen atom or a methyl group.
In addition, the electrophotographic apparatus according to another
embodiment of the present invention includes the
electrophotographic photosensitive member, a charging unit, an
exposing unit, a developing unit, and a transfer unit.
In addition, the process cartridge according to another embodiment
of the present invention supports the electrophotographic
photosensitive member integrally with at least one unit selected
from the group consisting of a charging unit, a developing unit, a
transfer unit, and a cleaning unit, in which the process cartridge
is detachably attachable to an electrophotographic apparatus main
body.
Further, a method of producing an electrophotographic
photosensitive member according to still another embodiment of the
present invention is a method of producing an electrophotographic
photosensitive member including a support and a photosensitive
layer above the support, including:
(i) forming a coating film of a coating solution for a surface
layer which is a composition containing a hole transporting
compound represented by the following Formula (1); and
(ii) forming the surface layer of the electrophotographic
photosensitive member by a polymerization reaction of the
composition containing the hole transporting compound represented
by the following Formula (1) in the coating film:
##STR00002##
in Formula (1), R.sup.1 and R.sup.2 independently represent an
alkyl group having 2 or more and 8 or less carbon atoms, R.sup.3
and R.sup.4 independently represent a hydrogen atom or an alkyl
group having 4 or less carbon atoms, R.sup.11 and R.sup.13
independently represent an alkylene group having 3 or more and 6 or
less carbon atoms, and R.sup.2 and R.sup.14 independently represent
a hydrogen atom or a methyl group.
Further features of the present invention will become apparent from
the following description of exemplary embodiments with reference
to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram illustrating an example of a process
cartridge having an electrophotographic photosensitive member.
FIG. 2 is a schematic diagram illustrating an example of an
electrophotographic apparatus having the electrophotographic
photosensitive member.
FIG. 3 is a drawing illustrating an example of a pressure pattern
transferring apparatus for forming a concave portion on a
circumferential surface of the electrophotographic photosensitive
member.
FIG. 4A is a top view illustrating the outline of a mold.
FIG. 4B is a schematic cross-sectional view in an axial direction
of the electrophotographic photosensitive member of a convex
portion of the mold (a cross-sectional view in S-S' section of FIG.
4A).
FIG. 4C is a cross-sectional view in a circumferential direction of
the electrophotographic photosensitive member of the convex portion
of the mold (a cross-sectional view in T-T' section of FIG.
4A).
DESCRIPTION OF THE EMBODIMENTS
An electrophotographic photosensitive member of an embodiment of
the present invention includes a polymerization product of a
composition containing a hole transporting compound having a
polymerizable functional group in a surface layer, and the hole
transporting compound has a specific aminofluorene structure.
Hereinafter, a hole transporting compound having a polymerizable
functional group having these characteristics is also referred to
as a hole transporting compound according to the present
invention.
Generally, as a hole transporting compound used in an
electrophotographic photosensitive member, an arylamine compound
having excellent hole transport properties is widely used.
It is considered that the amine structure exhibits an electron
donating property, forms a molecular orbital between an aryl group
around a nitrogen atom and the like, and causes
oxidation/reduction, thereby expressing the hole transport
properties of the arylamine compound. On the other hand, it is
considered that the arylamine moiety is in the state of being
susceptible to a chemical reaction or the like since charge
transfer is actively performed through the repeated
electrophotographic process. In particular, it is considered that
the arylamine moiety tends to be susceptible to change such as
oxidation, by an action of energy of discharge in a charging step
and ozone or an oxidizing material produced by a discharge
phenomenon.
As a result, it is presumed that the chemical change of the
arylamine moiety has been caused. In particular, it is considered
that the chemical change of the hole transporting compound,
generation of a discharge product, and moisture from the
environment are combined in a high temperature and high humidity
environment, thereby causing resistance of a photosensitive member
surface to be decreased, and generating image failure such as a
so-called smeared image.
The present inventors searched for a hole transporting compound
which can suppress deterioration even through repeated
electrophotographic processes and function with high stability and
high durability, thereby completing the present invention.
The hole transporting compound according to the present invention
has the following characteristics. The hole transporting compound
according to the present invention is formed by a structure having
an alkyl group having a specific number of carbon atoms at a
specific position in a molecule. That is, the hole transporting
compound has an alkyl group having a specific number of carbon
atoms at a 9-position of fluorene, in the hole transporting
compound having a fluorene structure. It is considered that by
having the characteristics, the hydrophobicity of the hole
transporting compound can be improved to effectively decrease
affinity with moisture. As a result, a decrease in resistance can
be suppressed.
However, when the hole transporting compound has an alkyl group
having an excessive number of carbon atoms, specific electrical
properties may be deteriorated. In particular, when continuously
used in a low temperature and low humidity environment, a potential
fluctuation of bright portion potential of a photosensitive member
may be increased.
Along with the above problems, particularly in an
electrophotographic apparatus which outputs a color image, a tint
variation of the image occurs while continuous image output is
performed from the beginning of printing.
The present inventors conducted an intensive study, and as a
result, found that by using a polymerization product of a
composition containing a hole transporting compound according to
the present invention in a surface layer, the above problem can be
effectively improved.
It is considered that the above problem can be improved, since the
hole transporting compound according to the present invention has
an alkyl group having a specific number of carbon atoms at a site
which is unlikely to adversely affect a hole transport function,
thereby achieving both chemical stability and electrical
properties.
The hole transporting compound according to the present invention
is a compound represented by the following Formula (1) and has a
fluorene structure:
##STR00003##
in Formula (1), R.sup.1 and R.sup.2 independently represent an
alkyl group having 2 or more and 8 or less carbon atoms, R.sup.3
and R.sup.4 independently represent a hydrogen atom or an alkyl
group having 4 or less carbon atoms, R.sup.11 and R.sup.13
independently represent an alkylene group having 3 or more and 6 or
less carbon atoms, and R.sup.12 and R.sup.14 independently
represent a hydrogen atom or a methyl group.
The requirements essential to the hole transporting compound
according to the present invention are divided into each partial
structure of Formula (1) and described below.
In the hole transporting compound according to the present
invention, an alkyl group having 2 or more and 8 or less carbon
atoms represented by R.sup.1 and R.sup.2 is bonded at the
9-position of a so-called fluorene structure.
The fluorene structure is formed so that a 5-membered ring and a
6-membered ring are condensed, and has high planarity. On the other
hand, only the carbon atom positioned at the 9-position of the
fluorene structure is the carbon atom forming an sp.sup.3 hybrid
orbital, and is positioned in a direction different from a plane
formed by three fused rings. It is considered that due to the
positional relationship, a structure in which hole transport
properties are hardly inhibited even with a large number of carbon
atoms is formed.
For the above reasons, it is presumed that it is possible not to
inhibit hole transport properties, while an alkyl group having a
large number of carbon atoms is present in the vicinity of an
aromatic amino group of the hole transporting compound.
By the presence of the alkyl group having a large number of carbon
atoms, hydrophobicity of the hole transporting compound can be
improved and smeared image under a high temperature and high
humidity environment can be improved.
In the hole transporting structure of the above Formula (1), when
an alkyl group bonded at the 9-position of the fluorene structure
has an excessively long carbon chain, there is a possibility of
inhibiting the electrical properties, and thus, the alkyl group has
8 or less and more preferably 6 or less carbon atoms. More
preferably, the alkyl group has 2 or more and 5 or less carbon
atoms. Further, a propyl group is preferred.
It is considered that when the carbon chain of the alkyl group is
excessively long, steric hindrance becomes large due to an aromatic
amino group and the like and disorder on the surface layer becomes
high, thereby inhibiting hole transport properties.
Examples of the alkyl group represented by R.sup.1 and R.sup.2
include a methyl group, an ethyl group, an n-propyl group, an
isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl
group, a tert-butyl group, an n-pentyl group, an isopentyl group, a
neopentyl group, a tert-pentyl group, a cyclopentyl group, an
n-hexyl group, a 1-methylpentyl group, a 4-methyl-2-pentyl group, a
3,3-dimethylbutyl group, a 2-ethylbutyl group, a 1-methylhexyl
group, a 4-tert-butylcyclohexyl group, an n-heptyl group, a
2-methylheptyl group, an n-octyl group, and the like.
The hole transporting compound according to the present compound
may have an alkyl group having 4 or less carbon atoms represented
by R.sup.3 and R.sup.4. By having the alkyl group having 4 or less
carbon atoms represented by R.sup.3 and R.sup.4, solubility of the
hole transporting compound according to the present invention and
compatibility thereof with surrounding materials or the like are
improved. Since the alkyl group represented by R.sup.3 and R.sup.4
is directly bonded to a benzene ring of fluorene, an excessively
long carbon chain causes steric hindrance. Therefore, the alkyl
group represented by R.sup.3 and R.sup.4 has 4 or less carbon
atoms. Examples of the alkyl group represented by R.sup.3 and
R.sup.4 include a methyl group, an ethyl group, an n-propyl group,
an isopropyl group, an n-butyl group, an isobutyl group, a
sec-butyl group, a tert-butyl group, and the like.
The hole transporting compound according to the present invention
has an alkylene group represented by R.sup.11 and R.sup.13 between
a benzene ring and a polymerizable functional group, as shown in
Formula (1).
The partial structure is considered to affect an energy value of a
molecular orbital of the hole transporting compound. In particular,
the highest occupied molecular orbital (HOMO) in the molecular
orbital is related to hole transport properties, and having an
energy value in an appropriate range is important for hole
transport properties.
In particular, in order to suppress fluctuations in a bright
portion potential in a photosensitive member after repeated use
under a low temperature and low humidity environment, it is
important to design the molecule so that the HOMO energy value of
the hole transporting compound according to the present invention
can be maintained within an appropriate range.
That is, by optimizing the HOMO energy value of the hole
transporting compound contained in the surface layer under the
condition in which hole injection and transport properties are
likely to be deteriorated, such as a low temperature and low
humidity environment, injection and transport of charge from an
adjacent layer can be made better.
It is presumed that the hole transporting compound according to the
present invention has a fluorene structure in which a conjugated
structure is widely spread in a plane, and further the HOMO energy
value is within a specific range to produce a synergistic effect.
It is preferred that the HOMO energy value which is calculated by a
density functional method (B3LYP/6-31G*) of the compound
represented by Formula (1) is -4.9 (eV) or more and -4.7 (eV) or
less.
The alkylene group represented by R.sup.11 and R.sup.13 in Formula
(1) has 3 or more and 6 or less carbon atoms. When the alkylene
group represented by R.sup.11 and R.sup.13 has 3 or more carbon
atoms, the HOMO energy value of the hole transporting compound is
-4.9 (eV) or more, which does not fall below the appropriate
range.
In addition, when the alkylene has 6 or less carbon atoms, the
alkyl group in the vicinity of an aromatic amine structure has an
appropriate length, thereby maintaining hole transport properties.
When the alkylene group represented by R.sup.11 and R.sup.13 has
more than 7 carbon atoms, a component of the alkylene chain causing
steric hindrance is increased to be a factor of inhibiting hole
transport properties. As a result, residual potential of the
photosensitive member rises and the potential fluctuation under a
low temperature and low humidity environment increases.
Examples of the alkylene group represented by R.sup.11 and R.sup.13
include an n-propylene group, an iso-propylene group, an n-butylene
group, an iso-butylene group, a sec-butylene group, a tert-butylene
group, an n-pentylene group, a 1-methyl-n-butylene group, a
2-methyl-n-butylene group, a 3-methyl-n-butylene group, a
1,1-dimethyl-n-propylene group, a 1,2-dimethyl-n-propylene group, a
2,2-dimethyl-n-propylene group, a n-hexylene group, a
1-methyl-n-pentylene group, a 2-methyl-n-pentylene group, a
1,1-dimethyl-n-butylene group, a 1,2-dimethyl-n-butylene group, and
the like.
In Formula (1), a substitution position of the fluorene structure
of the amino group is preferably a so-called 2-position or
4-position of fluorene, from a viewpoint of easiness of compound
synthesis and electrical properties of the photosensitive member.
In particular, a structure substituted at the 2-position is
preferred.
In the electrophotographic photosensitive member according to an
embodiment of the present invention, it is preferred that the
surface layer includes a copolymerization product of the
composition containing the hole transporting compound represented
by Formula (1) and a compound represented by the following Formula
(2):
##STR00004##
in Formula (2), R.sup.21 and R.sup.22 independently represent an
alkyl group having 1 or more and 4 or less carbon atoms or a
substituted or unsubstituted benzyl group, in which the substituent
of the benzyl group is an alkyl group having 4 or less carbon
atoms, and R.sup.21 and R.sup.22 may be bonded to each other to
form a ring, R.sup.23 represents an alkyl group having 1 or more
and 4 or less carbon atoms, and R.sup.24 and R.sup.25 independently
represent a hydrogen atom or a methyl group.
The compound represented by Formula (2) does not have hole
transport properties. When the compound represented by Formula (2)
is used simultaneously with the hole transporting compound
represented by Formula (1), the effect of the present invention is
further improved, thereby improving smeared image under a high
temperature and high humidity environment and a potential
fluctuation when used repeatedly under a low temperature and low
humidity environment, in a well-balanced manner.
The compound represented by Formula (2) has an appropriate
molecular weight and molecular size, and is presumed to have an
effect of improving denseness of a film containing the compound
represented by Formula (1), thereby suppressing infiltration of
moisture from the environment into a membrane. In addition, since
the compound represented by Formula (2) has an appropriate low
molecular weight and serves to supplement physical strength of the
polymerization product, the compound has an effect of compensating
for film strength and improving wear resistance.
R.sup.21 and R.sup.22 independently represent an alkyl group having
1 or more and 4 or less carbon atoms or a substituted or
unsubstituted benzyl group. Examples of the substituent of the
benzyl group include an alkyl group having 4 or less carbon atoms.
Examples of the alkyl group include a methyl group, an ethyl group,
an n-propyl group, an isopropyl group, an n-butyl group, an
isobutyl group, a sec-butyl group, a tert-butyl group, and the
like.
In order to obtain the effect of the present application, it is
preferred that R.sup.21 and R.sup.22 are an alkyl group having 1 to
4 carbon atoms. The molecular weight becomes compact and it is easy
to improve denseness of the film. Further, it is preferred that at
least one of R.sup.21 and R.sup.22 is an alkyl group having 2 or
more carbon atoms. This makes it possible to optimally control
hydrophobicity and film denseness of the compound represented by
Formula (2), thereby improving electrical properties when used in
the surface of the photosensitive member.
R.sup.21 and R.sup.22 may be bonded to each other to form a ring.
When forming a ring, examples of the ring include a cyclopentane
ring, a cyclohexane ring, a cycloheptane ring, and the like.
R.sup.23 is an alkyl group having 1 or more and 4 or less carbon
atoms. It is preferred that R.sup.23 is a methyl group or an ethyl
group from a viewpoint of obtaining the effect of the present
invention.
When a ratio of the compound represented by Formula (2) to the hole
transporting compound represented by Formula (1) is excessive,
charge transporting properties of the surface layer are lowered.
Therefore, electrical properties are deteriorated and the potential
fluctuation after repeated use is increased. Accordingly, it is
preferred that the content of the hole transporting compound
represented by Formula (1) in a coating solution for a surface
layer is 50% by mass or more with respect to the total mass of the
hole transporting compound represented by Formula (1) and the
compound represented by Formula (2) in the coating solution for a
surface layer.
As a method for causing a polymerization reaction of the
composition, a method for imparting energy such as ultraviolet
rays, an electron beam, and heat, or a method for causing co-exist
of compounds, for example, an auxiliary agent such as a
polymerization initiator, an acid, an alkali, and a complex can be
used.
The polymerizable functional group of the hole transporting
compound represented by Formula (1) and the compound represented by
Formula (2) is an acryloyloxy group or a methacryloyloxy group,
from a viewpoint of wear resistance of the surface layer and a
polymerization reaction rate during polymerization.
Accordingly, R.sup.12 and R.sup.14, and R.sup.24 and R.sup.25
independently represent a hydrogen atom or a methyl group.
Examples of the hole transporting compound represented by Formula
(1) are shown below. However, the compound is not limited to the
following examples.
##STR00005## ##STR00006## ##STR00007## ##STR00008##
In addition, examples of the compound represented by Formula (2)
are shown below. However, the compound is not limited to the
following examples.
##STR00009## ##STR00010## ##STR00011##
Representative synthesis examples of the compound used in the
present invention are shown in the following.
Synthesis Example 1
A synthesis example of the hole transporting compound having a
difunctional polymerizable acryl group represented by Exemplary
Compound No. 1-7 is shown.
##STR00012##
As shown in Reaction Formula (1), synthesis of a triarylamine body
was carried out, using an iodine body and an amine compound. In a
reaction vessel, 94.5 parts of an iodine body, 34.5 parts of an
amine body in Reaction Formula (1), and 80 parts of
o-dichlorobenzene were mixed, 26.9 parts of potassium carbonate and
16.6 parts of copper powder were added thereto, and stirring was
performed at an internal temperature of about 210.degree. C. for
about 24 hours to perform a reaction. After the reaction,
filtration, washing with toluene, and concentration were performed
to obtain a crude product.
##STR00013##
Subsequently, the entire amount of the crude product obtained in
the above was used to hydrolyze the resulting intermediate to
obtain a hydroxyl group from an acetic acid ester, as shown in
Reaction Formula (2). The crude product obtained above was mixed
with 100 parts of tetrahydrofuran, 100 parts of methanol, and 70
parts of a 24% aqueous sodium hydroxide solution, heated to an
internal temperature of 60.degree. C., stirred, and reacted for 1
hour to carry out hydrolysis. After the reaction and extraction
with ethyl acetate from the reaction mixture, an organic layer was
washed with water, washed with brine, dehydrated, and concentrated.
Purification was performed by silica gel chromatography to obtain a
dihydroxy intermediate. The quantity was 36.9 parts and the yield
(after two steps of reaction) was 53.2%.
##STR00014##
36.5 parts of the dihydroxy intermediate obtained by the reaction,
365 parts of toluene, and 0.7 parts of 4-methoxyphenol were mixed,
and 11.8 parts of acrylic acid was charged into the reaction
vessel. 1.3 parts of p-toluene sulfonic acid monoanhydrate was
added, heating was performed under a reflux condition at
112.degree. C. for 6 hours, and an acrylation reaction was carried
out as shown in Reaction Formula (3).
After the reaction, cooling was performed, neutralization was
performed using a 10% aqueous sodium hydroxide solution, and
extraction was carried out with ethyl acetate. Washing with water,
dehydration, and concentration were performed to obtain a crude
product.
Subsequently, the crude product was purified by silica gel column
chromatography to obtain a hole transporting compound having a
polymerizable functional group represented by Exemplary Compound
No. 1-7. The quantity was 39.5 parts and the yield was 63.0%.
Further, a varnish containing the hole transporting compound
represented by Exemplary Compound No. 1-7 was obtained by adjusting
the solvent type and the solvent amount of the resulting hole
transporting compound. Likewise, other hole transporting compounds
represented by Formula (1) can be synthesized.
Synthesis Example 2
A synthesis example of a compound having a difunctional
polymerizable acryl group represented by Exemplary Compound No. 2-3
is shown.
##STR00015##
50 parts of 2-methylvaleraldehyde, 40.5 parts of 37% formaldehyde,
and 8.5 parts of benzyltrimethylammonium hydroxide (a 40% aqueous
solution) were mixed in an autoclave. Nitrogen gas was injected to
raise pressure to 0.5 MPa, and the mixture was stirred at
90.degree. C. for 1 hour, and the reaction was carried out as shown
in Reaction Formula (4). After completion of the reaction, the
reaction solution was cooled to room temperature and separated.
Washing with water and concentration were carried out to obtain
about 50 parts of a colorless liquid.
##STR00016##
50 parts of the colorless liquid, 52 parts of trimethylolpropane,
and 1 part of p-toluenesulfonic acid were mixed and stirred at room
temperature overnight to carry out the reaction as shown in
Reaction Formula (5). After completion of the reaction, the
reaction product was purified by column chromatography using silica
gel with ethyl acetate as a mobile phase to obtain about 30 parts
of a colorless oil.
##STR00017##
The colorless oil was subjected to dehydration condensation with
acrylic acid as shown in Reaction Formula (6), using chloroform as
a solvent, triethylamine as a catalyst, and
dicyclohexylcarbodiimide as a dehydration condensation agent. A
filtrate of the reaction product was concentrated and purified by
column chromatography using silica gel with
n-hexane/ethylacetate=4/1 as a mobile phase to obtain a colorless
liquid. Further, 4-methoxyphenol as a polymerization inhibitor was
added so that the concentration after the addition was 100 ppm, to
obtain a compound having a difunctional polymerizable acrylic group
represented by Exemplary Compound No. 2-3.
Likewise, other compounds represented by Formula (2) can be
synthesized.
The composition for forming the surface layer of the
electrophotographic photosensitive member according to an
embodiment of the present invention may further contain a known
hole transporting compound having a polymerizable functional group,
in addition to the hole transporting compound according to the
present invention, within the range of not disturbing the effect of
the present invention. As the known hole transporting compound
having a polymerizable functional group, an aromatic amine compound
may be used.
The composition may further contain other compounds having a
polymerizable functional group and not having hole transport
properties. The mechanical strength of the resulting polymerization
product can be further improved by using other compounds having
another polymerizable functional group in combination.
The polymerizable functional group of other compounds having a
polymerizable functional group and not having hole transport
properties may be the above-mentioned polymerizable functional
group. A radical polymerizable functional group such as a styryl
group, a vinyl group, an acryloyloxy group, and a methacryloyloxy
group is preferred. An acryloyloxy group or a methacryloyloxy group
is more preferred.
The surface layer may include various fine particles, from a
viewpoint of wear resistance. The fine particles may be inorganic
fine particles or organic fine particles. As the inorganic fine
particles, particles containing alumina, silica, zinc oxide, tin
oxide, titanium oxide, or the like are used.
As the organic fine particles, various organic resin fine particles
can be used. Examples of the organic resin fine particles include
particles containing a polyolefin resin, a polytetrafluoroethylene
resin, a polystyrene resin, a polyacrylic acid ester resin, a
polymethacrylic acid ester resin, a polyamide resin, a polyester
resin, a polyurethane resin, or the like.
A method of producing an electrophotographic photosensitive member
according to an embodiment of the present invention is a method of
producing an electrophotographic photosensitive member including a
support and a photosensitive layer above the support. The
production method includes (i) forming a coating film of a coating
solution for a surface layer which is a composition containing the
hole transporting compound represented by Formula (1). The
production method further includes (ii) forming the surface layer
of the electrophotographic photosensitive member by a
polymerization reaction of the composition containing the hole
transporting compound represented by Formula (1) in the coating
film.
Formation of the surface layer in step (ii) can be carried out by
drying and/or curing the coating film formed in step (i).
It is preferred that step (i) is forming a coating film of a
coating solution for a surface layer which is a composition
containing the hole transporting compound represented by Formula
(1) and the compound represented by Formula (2), and
step (ii) is forming the surface layer by a polymerization reaction
of the composition containing the hole transporting compound
represented by Formula (1) and the compound represented by Formula
(2) in the coating film.
It is preferred that a content of the hole transporting compound
represented by Formula (1) in the coating solution for a surface
layer is 50% by mass or more with respect to the total mass of the
hole transporting compound represented by Formula (1) and the
compound represented by Formula (2) in the coating solution for a
surface layer.
As a solvent used in the coating solution for a surface layer, an
alcohol-based solvent, a sulfoxide-based solvent, a ketone-based
solvent, an ether-based solvent, an ester-based solvent, an
aliphatic halogenated hydrocarbon-based solvent, an aliphatic
hydrocarbon-based solvent, an aromatic hydrocarbon-based solvent,
or the like can be used.
Examples of a method of curing the coating film of the coating
solution for a surface layer (carrying out a polymerization
reaction of the composition containing the hole transporting
compound according to the present invention) include methods using
heat, light (such as ultraviolet rays), or radiation (such as an
electron beam). Among the methods, a method using radiation is
preferred, and among the radiation, an electron beam is more
preferred.
When polymerization is performed using the electron beam, a highly
dense (high density) three-dimensional network structure is
obtained and wear resistance is improved, which is thus preferred.
In addition, since the polymerization reaction becomes efficient in
a short time, productivity is also increased. When the electron
beam is irradiated, examples of an accelerator include a scanning
type, an electro curtain type, a broad beam type, a pulse type, a
laminar type, or the like.
When the electron beam is used, it is preferred that the
acceleration voltage of the electron beam is 150 kV or less, from a
viewpoint that deterioration of material properties by the electron
beam can be suppressed without impairing polymerization efficiency.
In addition, an electron beam absorption dose on the surface of the
coating film of the coating solution for a surface layer is
preferably 5 kGy or more and 50 kGy or less and more preferably 10
kGy or more and 30 kGy or less.
In addition, when the hole transporting compound according to the
present invention is polymerized using the electron beam, for the
purpose of suppressing a polymerization inhibiting action by
oxygen, it is preferred that an electron beam is irradiated in an
inert gas atmosphere and then heating is performed in an inert gas
atmosphere. Examples of the inert gas include nitrogen, argon,
helium, or the like.
Next, the entire configuration of the electrophotographic
photosensitive member according to an embodiment of the present
invention will be described.
<Electrophotographic Photosensitive Member>
The electrophotographic photosensitive member in the present
invention has a photosensitive layer above a support. It is
preferred that the photosensitive layer is a laminate type
photosensitive layer in which a charge generation layer and a
charge transport layer are layered in this order. If necessary, an
electroconductive layer or an undercoating layer may be provided
between the charge generation layer and the support, and a
protection layer may be provided on the charge transport layer.
The composition for forming the surface layer of the
electrophotographic photosensitive member contains the hole
transporting compound according to the present invention. When the
electrophotographic photosensitive member has the protection layer,
the surface layer of the electrophotographic photosensitive member
in the present invention refers to a protection layer, and when the
electrophotographic photosensitive member does not have the
protection layer, the surface layer refers to a charge transport
layer if the photosensitive layer is the laminate type
photosensitive layer. The photosensitive layer may be composed of a
single layer type photosensitive layer containing both a charge
generation material and a charge transport material, and in this
case, when the electrophotographic photosensitive member has the
protection layer, the surface layer refers to the photosensitive
layer.
<Support>
The support is preferably an electroconductive support made of an
electroconductive material. Examples of the material of the support
include metals or alloys such as iron, copper, gold, silver,
aluminum, zinc, titanium, lead, nickel, tin, antimony, indium,
chromium, aluminum alloy, and stainless steel. In addition, a metal
support or a resin support having a coating formed by vacuum
deposition of aluminum, an aluminum alloy, an indium oxide-tin
oxide alloy, or the like can be used. In addition, a support
obtained by impregnating plastic or paper with electroconductive
particles such as carbon black, tin oxide particles, titanium oxide
particles, or silver particles, or a support containing an
electroconductive resin can also be used. Examples of the shape of
the support include cylindrical, belt-like, sheet-like, plate-like
shapes, or the like, but a cylindrical shape is the most
common.
The surface of the support may be subjected to treatment such as
cutting treatment, roughening treatment, or alumite treatment, from
a viewpoint of suppression of interference fringe by laser light
scattering, improvement of surface defects of the support,
improvement of conductivity of the support, or the like.
<Electroconductive Layer>
An electroconductive layer may be provided between the support and
an undercoating layer or a charge generation layer described later,
for the purpose of suppressing interference fringes by scattering
of a laser or the like, controlling resistance, or covering a
scratch of the support.
The electroconductive layer can be formed by applying a coating
solution for an electroconductive layer obtained by dispersing
carbon black, an electroconductive pigment, a resistance adjustment
pigment, and the like with a binder resin, and drying the obtained
coating film. To the coating solution for an electroconductive
layer, a compound which is cured and polymerized by heating,
ultraviolet irradiation, radiation irradiation, or the like may be
added. The conductive layer formed by dispersing an
electroconductive pigment and a resistance adjustment pigment has a
surface which tends to be roughened.
A film thickness of the conductive layer is preferably 0.1 .mu.m or
more and 50 .mu.m or less, more preferably 0.5 .mu.m or more and 40
.mu.m or less, and still more preferably 1 .mu.m or more and 30
.mu.m or less.
Examples of the binder resin used in the conductive layer include
polymers and copolymers of vinyl compounds such as styrene, vinyl
acetate, vinyl chloride, acrylic acid ester, methacrylic acid
ester, vinylidene fluoride, or trifluoroethylene; a polyvinyl
alcohol resin, a polyvinyl acetal resin, a polycarbonate resin, a
polyester resin, a polysulfone resin, a polyphenylene oxide resin,
a polyurethane resin, a cellulose resin, a phenol resin, a melamine
resin, a silicon resin, an epoxy resin, and an isocyanate
resin.
Examples of the conductive pigment and the resistance adjustment
pigment include particles of metal (alloy) such as aluminum, zinc,
copper, chromium, nickel, silver, or stainless steel, or pigments
with these particles deposited on the surface of plastic particles.
In addition, particles of metal oxides such as zinc oxide, titanium
oxide, tin oxide, antimony oxide, indium oxide, bismuth oxide,
indium oxide doped with tin, tin oxide doped with antimony or
tantalum, and the like may be also used. These may be used alone or
in combination of two or more.
<Undercoating Layer>
An undercoating layer (intermediate layer) may be provided between
the support or the conductive layer and the charge generation
layer, for the purpose of improving adhesion of the charge
generation layer, improving hole injection properties from the
support, and protecting the charge generation layer against
electrical breakdown.
The undercoating layer can be formed by applying a coating solution
for an undercoating layer obtained by dissolving a binder resin in
a solvent and drying the resulting coating film.
Examples of the binder resins used for the undercoating layer
include a polyvinyl alcohol resin, a poly-N-vinylimidazole, a
polyethylene oxide resin, ethyl cellulose, an ethylene-acrylic acid
copolymer, casein, a polyamide resin, an N-methoxymethylated 6
nylon resin, a copolymerized nylon resin, a phenol resin, a
polyurethane resin, an epoxy resin, an acrylic resin, a melamine
resin, a polyester resin, or the like.
The undercoating layer may further include metal oxide particles.
Examples of the metal oxide particles include particles containing
titanium oxide, zinc oxide, tin oxide, zirconium oxide, or aluminum
oxide. In addition, the metal oxide particles may be metal oxide
particles of which the surface is treated with a surface treatment
agent such as a silane coupling agent.
The thickness of the undercoating layer is preferably 0.05 .mu.m or
more and 30 .mu.m or less, and more preferably 1 .mu.m or more and
25 .mu.m or less. The undercoating layer may further include
organic resin particles and a leveling agent.
<Photosensitive Layer>
The photosensitive layer of the electrophotographic photosensitive
member is mainly classified into (1) a laminate type photosensitive
layer and (2) a single layer type photosensitive layer. (1) The
laminate type photosensitive layer has a charge generation layer
containing a charge generating material and a charge transport
layer containing a charge transport material. (2) The single layer
type photosensitive layer has a photosensitive layer containing
both the charge generating material and the charge transport
material.
(1) Laminate Type Photosensitive Layer
The laminate type photosensitive layer has a charge generation
layer and a charge transport layer.
(1-1) Charge Generation Layer
The charge generation layer is formed by applying a coating
solution for a charge generation layer obtained by dispersing a
charge generating material with a binder resin and a solvent to
form a coating film, and drying the resulting coating film. In
addition, the charge generation layer may be a deposited film of a
charge generating material.
Examples of the charge generating material used in the charge
generation layer include azo pigments, phthalocyanine pigments,
indigo pigments, perylene pigments, polycyclic quinone pigments,
squarylium dyes, pyrylium salts, thiapyrylium salts,
triphenylmethane dyes, quinacridone pigments, azulenium salt
pigments, cyanine dyes, anthanthrone pigments, pyranthrone
pigments, xanthene dyes, quinoneimine dyes, styryl dyes, and the
like. The charge generating material may be used alone or in
combination or two or more. Among the charge generating materials,
phthalocyanine pigments and azo pigments are preferred, and in
particular, phthalocyanine pigments are more preferred, from a
viewpoint of sensitivity.
Among the phthalocyanine pigments, particularly, oxytitanium
phthalocyanine, chlorogallium phthalocyanine, and hydroxygallium
phthalocyanine exhibit excellent charge generation efficiency.
Further, among the hydroxygallium phthalocyanines, a hydroxygallium
phthalocyanine crystal of a crystal form having a peak at Bragg
angles 2.theta. of 7.4.degree..+-.0.3.degree. and
28.2.degree..+-.0.3.degree. in CuK.alpha. characteristic X-ray
diffraction is more preferred, from a viewpoint of sensitivity.
Examples of the binder resin used in the charge generation layer
include polymers of vinyl compounds such as styrene, vinyl acetate,
vinyl chloride, acrylic acid ester, methacrylic acid ester,
vinylidene fluoride, and trifluoroethylene, and a polyvinyl alcohol
resin, a polyvinyl acetal resin, a polycarbonate resin, a polyester
resin, a polysulfone resin, a polyphenylene oxide resin, a
polyurethane resin, a cellulose resin, a phenol resin, a melamine
resin, a silicon resin, an epoxy resin, and the like.
It is preferred that a mass ratio of the charge generating material
to the binder resin is in a range of 1:0.3 to 1:4.
The film thickness of the charge generation layer is preferably
0.05 .mu.m or more and 1 .mu.m or less, and more preferably 0.1
.mu.m or more and 0.5 .mu.m or less.
(1-2) Charge Transport Layer
The charge transport layer can be formed by forming a coating film
of a coating solution for a charge transport layer in which a
charge transport material and a binder resin are mixed in a solvent
and drying the coating film. When the charge transport layer is a
surface layer, the coating solution for a charge transport layer
which is a composition for forming a charge transport layer as a
surface layer, contains the hole transporting compound according to
the present invention, as described above. Hereinafter, the charge
transport material and the binder resin used in the charge
transport layer will be described.
Examples of the charge transport material include carbazole
compounds, hydrazone compounds, N,N-dialkylaniline compounds,
diphenylamine compounds, triphenylamine compounds, triphenylmethane
compounds, pyrazoline compounds, styryl compounds, stilbene
compounds, and the like.
Examples of the binder resin include acrylic acid ester,
methacrylic acid ester, a polyvinyl alcohol resin, a polyvinyl
acetal resin, a polycarbonate resin, a polyester resin, and the
like. In addition, curable resins such as a curable phenolic resin,
a curable urethane resin, a curable melamine resin, a curable epoxy
resin, a curable acrylic resin, and a curable methacrylic resin can
be used.
Examples of the solvent used in the coating solution for a charge
transport layer include an alcohol-based solvent, a sulfoxide-based
solvent, a ketone-based solvent, an ether-based solvent, an
ester-based solvent, an aliphatic halogenated hydrocarbon-based
solvent, an aromatic hydrocarbon-based solvent, and the like.
When the charge transport layer is a surface layer, it is preferred
that a film thickness of the charge transport layer is 5 .mu.m or
more and 40 .mu.m or less.
When the charge transport layer is not a surface layer, a film
thickness of the charge transport layer is preferably 1 .mu.m or
more and 100 .mu.m or less, more preferably 3 .mu.m or more and 50
.mu.m or less, and still more preferably 5 .mu.m or more and 40
.mu.m or less.
(2) Single Layer Type Photosensitive Member
The photosensitive layer of the single layer type photosensitive
member can be formed by preparing a coating solution for a
photosensitive layer containing a charge generating material,
charge transport material, a resin, and a solvent, forming the
coating film thereof, and drying the coating film. Examples of the
charge generating material, the charge transport material, and the
resin are the same as the examples of the materials in the above
"(1) laminate type photosensitive layer".
When the single layer type photosensitive member does not have a
protection layer, the photosensitive layer of the single layer type
photosensitive member is the surface layer in the present
invention. That is, the coating solution for a photosensitive
layer, which is a composition for forming a photosensitive layer as
a surface layer, contains the hole transporting compound according
to the present invention. It is preferred that a film thickness of
the photosensitive layer of the single layer type photosensitive
member is 5 .mu.m or more and 40 .mu.m or less. When the single
layer type photosensitive member has a protection layer, the
protection layer is the surface layer in the present invention. The
coating solution for a protection layer, which is a composition for
forming a protection layer as a surface layer, contains the hole
transporting compound of the present invention.
<Protection Layer>
The electrophotographic photosensitive member according to an
embodiment of the present invention may have a protection layer on
the photosensitive layer. When the electrophotographic
photosensitive member has a protection layer, the protection layer
is the surface layer in the present invention.
As described above, the coating solution for a protection layer,
which is a composition for forming a protection layer as a surface
layer, contains the hole transporting compound according to the
present invention.
Examples of a reaction method for forming the protection layer
include a thermal polymerization reaction, a photopolymerization
reaction, a radiation polymerization reaction, and the like.
The protection layer may include an additive such as an
antioxidant, an ultraviolet light absorber, a plasticizer, a
leveling agent, a sliding property imparting agent, and an abrasion
resistance improver.
Specifically, examples of the additive include a hindered phenol
compound, a hindered amine compound, a sulfur compound, a
phosphorus compound, a benzophenone compound, a siloxane-modified
resin, a silicone oil, fluorine resin particles, polystyrene resin
particles, polyethylene resin particles, silica particles, alumina
particles, boron nitride particles, and the like.
The protection layer may include conductive particles and/or a
charge transport material and a resin, in a range of not impairing
the effect of the present invention.
Examples of the conductive particles include particles of metal
oxides such as titanium oxide, zinc oxide, tin oxide, and indium
oxide.
Examples of the charge transport material include a benzidine
compound, a triarylamine compound, and the like.
Examples of the resin include a polyester resin, an acryl resin, a
phenoxy resin, a polycarbonate resin, a polystyrene resin, a phenol
resin, a melamine resin, an epoxy resin, and the like. Among them,
a polycarbonate resin, a polyester resin, and an acryl resin are
preferred.
It is preferred that a film thickness of the protection layer is
0.5 .mu.m or more and 20 .mu.m or less.
The protection layer can be formed by preparing a coating solution
for a protection layer containing each of the above materials and a
solvent, forming the coating film thereof, and drying and/or curing
the coating film. Examples of the solvent used in the coating
solution include an alcohol-based solvent, a ketone-based solvent,
an ether-based solvent, a sulfoxide-based solvent, an ester-based
solvent, an aromatic hydrocarbon-based solvent, and the like.
It is possible to add various additives to each layer of the
electrophotographic photosensitive member of the present invention.
Specifically, examples of the additive include an organic pigment,
an organic dye, a coating film surface adjusting agent, an electron
transport agent, oil, wax, an antioxidant, a light absorber, a
polymerization initiator, a radical deactivator, organic resin fine
particles, inorganic particles, and the like.
On the surface of each layer of the electrophotographic
photosensitive member, surface processing may be performed using a
polishing sheet, a shape transfer type member, glass beads,
zirconia beads, and the like. In addition, concave and convex
portions may be formed on the surface using a constituent material
of the coating solution. When the coating solution of each of the
layers is applied, any known coating method such as a dip coating
method, a spray coating method, a circular amount regulation (ring)
coating method, a spin coating method, a roller coating method, a
Meyer bar coating method, and a blade coating method can be
used.
Next, a process cartridge and an image formation process according
to an embodiment of the present invention will be described.
The process cartridge according to an embodiment of the present
invention supports the electrophotographic photosensitive member
according to an embodiment of the present invention integrally with
at least one unit selected from the group consisting of a charging
unit, a developing unit, a transfer unit, and a cleaning unit, and
is detachably attachable to an electrophotographic apparatus main
body.
An example of the configuration of the process cartridge according
to an embodiment of the present invention is illustrated in FIG. 1.
In FIG. 1, a cylindrical electrophotographic photosensitive member
1 is rotationally driven at a predetermined circumferential speed
in an arrow direction. A circumferential surface of the
rotationally driven electrophotographic photosensitive member 1 is
uniformly charged to a positive or negative predetermined potential
by a charging unit 2. Next, the charged circumferential surface of
electrophotographic photosensitive member 1 receives exposure light
(image exposure light) 3 output from an exposing unit (not
illustrated) such as slit exposure or laser beam scanning exposure.
Thus, an electrostatic latent image corresponding to a target image
is sequentially formed on the circumferential surface of the
electrophotographic photosensitive member 1. As a voltage applied
to the charging unit (charging roller or the like) 2, either of a
voltage obtained by superimposing an alternating current component
on a direct current component or a voltage having only a direct
current component may be used.
The electrostatic latent image formed on the circumferential
surface of the electrophotographic photosensitive member 1 is
developed by a toner contained in a developer of a developing unit
4 to form a toner image. Subsequently, the toner image formed and
carried on the circumferential surface of the electrophotographic
photosensitive member 1 is sequentially transferred from a transfer
unit 5 (transfer roller or the like) to a transfer material 6
(paper, an intermediate transfer body, or the like) by a transfer
bias. The transfer material 6 is fed in synchronization with a
rotation of the electrophotographic photosensitive member 1.
After de-electrification by pre-exposure light 7 from a
pre-exposing unit (not illustrated), the surface of the
electrophotographic photosensitive member 1 is cleaned by removing
the transfer residual toner by the cleaning unit 8, and the
electrophotographic photosensitive member 1 is repeatedly used for
image formation. The pre-exposing unit may be before or after the
cleaning step, and the pre-exposing unit is not necessarily
required.
The electrophotographic photosensitive member 1 may be mounted on
an electrophotographic apparatus such as a copying machine or a
laser beam printer. In addition, a process cartridge 9 which is
configured by storing a plurality of elements among the constituent
elements such as the electrophotographic photosensitive member 1,
the charging unit 2, the developing unit 4, and the cleaning unit 8
in a container and integrally supporting the elements may be
configured to be detachably attachable to an electrophotographic
apparatus main body. In FIG. 1, the process cartridge 9 integrally
supports the electrophotographic photosensitive member 1, the
charging unit 2, the developing unit 4, and the cleaning unit 8 and
is detachably attachable to the electrophotographic apparatus main
body.
Next, the electrophotographic apparatus according to an embodiment
of the present invention will be described.
The electrophotographic apparatus according to an embodiment of the
present invention includes the electrophotographic photosensitive
member according to an embodiment of the present invention, a
charging unit, an exposing unit, a developing unit, and a transfer
unit.
An example of the configuration of the electrophotographic
apparatus according to an embodiment of the present invention is
illustrated in FIG. 2. Yellow, magenta, cyan, black, a process
cartridge for yellow 17, a process cartridge for magenta 18, a
process cartridge for cyan 19, and a process cartridge for black
20, which correspond to each color, are provided in parallel along
an intermediate transfer member 10. As illustrated in FIG. 2, it is
not necessary to unify the diameter, constituent materials,
developer, charging method, and other unit of the
electrophotographic photosensitive member. For example, in the
electrophotographic apparatus of FIG. 2, the diameter of the
electrophotographic photosensitive member for black is larger than
the diameters of the electrophotographic photosensitive member for
other colors (yellow, magenta, and cyan). In addition, while a
charging method for other colors is a method of applying a voltage
in which an alternating current component is superimposed on a
direct current component, a charging method for black adopts a
method of using corona discharge.
When an image forming operation is started, the toner image of each
color is sequentially superimposed on the intermediate transfer
member 10, following the above-described image forming process. At
the same time, a transfer paper 11 is fed from a paper feed tray 13
by a paper feed path 12 and is fed to a secondary transfer unit 14
in timing with the rotational operation of the intermediate
transfer member 10. The toner image on the intermediate transfer
member 10 is transferred to the transfer paper 11 by a transfer
bias from the secondary transfer unit 14. The toner image
transferred on the transfer paper 11 is conveyed along the paper
feed path 12, fixed on the transfer paper by a fixing unit 15, and
discharged from a paper discharge unit 16.
According to the present invention, there is provided an
electrophotographic photosensitive member which has wear
resistance, suppresses smeared image under a high temperature and
high humidity environment, and also, has a small potential
fluctuation when repeatedly used under a low temperature and low
humidity environment. In addition, an electrophotographic apparatus
equipped with the electrophotographic photosensitive member is
provided. Further, a process cartridge equipped with the
electrophotographic photosensitive member is provided. Further, a
method of producing the electrophotographic photosensitive member
is provided.
EXAMPLES
Hereinafter, the present invention will be described in more detail
by way of specific examples. In the Examples, "parts" means "parts
by mass". In addition, an electrophotographic photosensitive member
is hereinafter also simply referred to as "a photosensitive
member".
<Manufacture of Electrophotographic Photosensitive
Member>
Example 1
A cylindrical aluminum cylinder having an outer diameter of 30.0
mm, a length of 357.5 mm, and a thickness of 0.7 mm was used as a
support (electroconductive support).
Next, 10 parts of zinc oxide particles (specific surface area: 19
m.sup.2/g, powder resistivity: 4.7.times.10.sup.6 .OMEGA.cm) were
mixed with stirring with 50 parts of toluene, and 0.08 parts of a
silane coupling agent was added thereto and stirred for 6 hours.
Thereafter, toluene was distilled off under reduced pressure, and
the residue was dried by heating at 130.degree. C. for 6 hours, and
surface-treated zinc oxide particles were obtained. As the silane
coupling agent, KBM 602 (compound name:
N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane) manufactured
by Shin-Etsu Chemical Co., Ltd. was used.
Next, 15 parts of a polyvinylbutyral resin (weight average
molecular weight: 40000, product name: BM-1, manufactured by
Sekisui Chemical Company, Limited) and 15 parts of blocked
isocyanate (product name: Duranate TPA-B80E, manufactured by Asahi
Kasei Chemicals Corp.) were prepared. These were dissolved in a
mixed solution of 73.5 parts of methylethyl ketone and 73.5 parts
of 1-butanol. 80.8 parts of the surface-treated zinc oxide
particles and 0.8 parts of 2,3,4-trihydroxybenzophenone
(manufactured by Wako Pure Chemical Industries, Ltd.) were added to
the solution, and dispersed under an atmosphere at 23.+-.3.degree.
C. for 3 hours by a sand mill using glass beads having a diameter
of 0.8 mm. After dispersion, 0.01 parts of silicone oil (product
name: SH28PA, manufactured by Dow Corning Toray Co., Ltd.), 5.6
parts of crosslinked polymethyl methacrylate (PMMA) particles
(product name: TECHPOLYMER SSX-102, manufactured by Sekisui
Plastics Co., Ltd., average primary diameter of 2.5 .mu.m) were
added and stirred to prepare a coating solution for an undercoating
layer.
The coating solution for an undercoating layer was dip-coated on
the support to form a coating film, and the resulting coating film
was dried at 160.degree. C. for 40 minutes to form an undercoating
layer having a film thickness of 18 .mu.m.
Next, 2 parts of a hydroxygallium phthalocyanine crystal (charge
generating material) in a crystalline form having peaks at
7.4.degree. and 28.2.degree. with a Bragg angle of 20.+-.0.2 in
CuK.alpha. characteristic X-ray diffraction were prepared. Further,
0.02 parts of a calixarene compound represented by the following
Structural Formula (A), 1 part of polyvinyl butyral (product name:
S-LEC BX-1, manufactured by Sekisui Chemical Co., Ltd.), and 60
parts of cyclohexanone were prepared. These were placed in a sand
mill using glass beads having a diameter of 1 mm, and dispersed for
4 hours. Thereafter, 70 parts of ethyl acetate was added to prepare
a coating solution for a charge generation layer. The coating
solution for a charge generation layer was dip-coated on the
undercoating layer, and the resulting coating film was dried at
90.degree. C. for 15 minutes to form a charge generation layer
having a film thickness of 0.17.mu.m.
##STR00018##
Next, the following materials were prepared. 6 parts of a compound
represented by the following Structural Formula (B) 3 parts of a
compound represented by the following Structural Formula (C) 1 part
of a compound represented by the following Structural Formula (D)
10 parts of a bisphenol Z type polycarbonate resin (product name:
Iupilon Z400, manufactured by Mitsubishi Engineering-Plastics
Corporation)
These were dissolved in a mixed solvent of 35 parts of o-xylene, 35
parts of dimethoxymethane, and 30 parts of methyl benzoate to
prepare a coating solution for a charge transport layer. The
coating solution for a charge transport layer was dip-coated on the
charge generation layer, and the resulting coating film was dried
at 110.degree. C. for 50 minutes, thereby forming a charge
transport layer having a film thickness of 18.mu.m.
##STR00019##
1.5 parts of a fluorine atom-containing acryl resin having a
repeating structural unit represented by the following Formula (F1)
and a repeating structural unit represented by the following
Formula (F2) (weight average molecular weight: 83,000,
copolymerization ratio (F1)/(F2)=1/1 (molar ratio)):
##STR00020##
was dissolved in a mixed solvent of 45 parts of 1-propanol and 45
parts of ZEORORA H (manufactured by Zeon Corporation). Thereafter,
30 parts of fluorinated ethylene resin powder (product name: Lubron
L-2, manufactured by DAIKIN INDUSTRIES, Ltd.) was added, and
dispersion was performed with a high pressure disperser (product
name: Microfluidizer M-110EH, manufactured by Microfluidics
Corporation, US) to obtain a fluorinated ethylene resin
dispersion.
4 parts of the hole transporting compound represented by Exemplary
Compound No. 1-1, 8 parts of the fluorinated ethylene resin
dispersion, 3 parts of 1-propanol, and 3 parts of ZEORORA H were
stirred and uniformly dispersed to prepare a coating solution for a
protection layer.
The coating solution for a protection layer was dip-coated on the
charge transport layer, the resulting coating film was dried at
50.degree. C. for 10 minutes, and polymerization curing treatment
was carried out by electron beam irradiation and heating under the
following conditions.
Under an atmosphere with an oxygen concentration of 50 ppm or less,
an electron beam was irradiated under the conditions of an
irradiation distance of 30 mm, an acceleration voltage of 70 kV, a
beam current of 8 mA, and an irradiation time of 3.0 seconds, using
an electron beam irradiation apparatus, while the aluminum cylinder
was rotated at a speed of 300 rpm. After electron beam irradiation,
the surface of the protection layer coating film was allowed to
reach 135.degree. C. for 24 seconds, rapidly using an induction
heating device, under the same condition of an oxygen concentration
of 50 ppm or less.
Next, the above-described aluminum cylinder was taken out to the
atmosphere and further heated at 100.degree. C. for 12 minutes,
thereby forming a protection layer having a film thickness of 5
.mu.m.
Next, a die member (mold) was installed in a pressure pattern
transferring apparatus, and surface processing was performed on the
manufactured electrophotographic photosensitive member before
forming a concave portion.
Specifically, a mold illustrated in FIGS. 4A to 4C was installed in
a pressure pattern transferring apparatus of a configuration having
a mold 22, a pressurizing member 23, and a support member 24 which
is generally illustrated in FIG. 3, and surface processing was
performed on the manufactured electrophotographic photosensitive
member 21 before forming the concave portion. FIGS. 4A to 4C are
drawings illustrating a mold used in the Examples and the
Comparative Examples. FIG. 4A is a top view illustrating an outline
of a mold, and FIG. 4B is a schematic cross-sectional view in an
axial direction of the electrophotographic photosensitive member 21
of a convex portion of the mold (a cross-sectional view in S-S'
section of FIG. 4A). FIG. 4C is a cross-sectional view in a
circumferential direction of the electrophotographic photosensitive
member 21 of the convex portion of the mold (a cross-sectional view
in T-T' section of FIG. 4A). The mold illustrated in FIGS. 4A to 4C
has a convex portion having a maximum width (a maximum width in an
axial direction of the electrophotographic photosensitive member 21
when the convex portion on the mold is viewed from above) X: 50
.mu.m, a maximum length (a maximum length in a circumferential
direction of the electrophotographic photosensitive member 21 when
the convex portion on the mold is viewed from above) Y: 75 .mu.m,
an area ratio of 56%, and a height H: 4 .mu.m. The area ratio
refers to a ratio of an area of the convex portion occupied on the
entire area when the mold is viewed from above. At the time of
processing, the temperature of the electrophotographic
photosensitive member 21 and the mold was controlled so that the
surface temperature of the electrophotographic photosensitive
member 21 was 120.degree. C. Then, the electrophotographic
photosensitive member 21 was rotated in a circumferential direction
to form a concave portion on the entire surface layer
(circumferential surface) of the electrophotographic photosensitive
member 21, while the electrophotographic photosensitive member and
the pressurizing member were pressed against the mold at a pressure
of 7.0 MPa. Thus, the electrophotographic photosensitive member 21
was manufactured.
The surface of the resulting electrophotographic photosensitive
member 21 was observed by magnification with a 50.times. lens with
a laser microscope (product name: X-100, manufactured by KEYENCE
CORPORATION), so that the concave portion provided on the surface
of the electrophotographic photosensitive member 21 was observed.
At the time of observation, an adjustment was performed so that
there is no inclination in a longitudinal direction of the
electrophotographic photosensitive member 21 and in a
circumferential direction, the apex of the arc of the
electrophotographic photosensitive member 21 was in focus. The
image subjected to observation by magnification was connected by an
image connection application to obtain a square area of 500 .mu.m
on a side. Then, for the obtained result, the image processing
height data was selected with an attached image analysis software,
and the filter processing was performed by a filter type
median.
As a result of the observation, the depth of the concave portion
was 2 .mu.m, a width of an opening in an axial direction was 50
.mu.m, a length of the opening in a circumferential direction was
75 and an area was 140000 .mu.m.sup.2. The area is the area of the
concave portion when the surface of the electrophotographic
photosensitive member 21 is viewed from above, and means the area
of the opening of the concave portion.
The photosensitive member according to Example 1 was manufactured
as described above.
Examples 2 to 11 and Comparative Examples 1 to 8
Hole transporting compounds shown in Table 1 were used respectively
instead of the hole transporting compound used in the preparation
of the coating solution for a protection layer in Example 1. Other
than that, the photosensitive members according to Examples 2 to 11
and Comparative Examples 1 to 8 were manufactured in the same
manner as in Example 1. Comparative Compounds Nos. 1 to 8 used in
Comparative Examples 1 to 8 are shown.
##STR00021##
Examples 12 to 18
Hole transporting compounds in types and amounts shown in Table 1,
respectively and the compound represented by Formula (2) were used
instead of the hole transporting compound used in the preparation
of the coating solution for a protection layer in Example 1. Other
than that, the photosensitive members according to Examples 12 to
18 were manufactured in the same manner as in Example 1.
Comparative Example 9
An electrophotographic photosensitive member was manufactured in
the same manner as in Example 1, except that the protection layer
was formed as follows.
A coating solution for a protection layer was prepared by
dissolving 4 parts of the compound represented by the following
Comparative Compound No. 9 in 100 parts of tetrahydrofuran. The
coating solution for a protection layer was spray-coated on a
charge transport layer, dried, and curing-polymerized under the
same conditions as in Example 1 to form a protection layer.
##STR00022##
Comparative Example 10
An electrophotographic photosensitive member was manufactured in
the same manner as in Example photosensitive member 1, except that
the protection layer was formed as follows.
First, the following materials were prepared. 1 part of a compound
represented by the following Comparative Compound No. 10, 1 part of
trimethylolpropane triacrylate, 0.2 parts of
1-hydroxycyclohexylphenyl ketone as a polymerization initiator, and
0.2 parts of 2,2-bis(4,4-di-t-butylperoxycyclohexyl) propane, 58
parts of tetrahydrofuran as a coating material solvent
These were mixed to prepare a coating solution for a protection
layer. The coating solution for a protection layer was spray-coated
on a charge hole transport layer, dried, and curing-polymerized
under the same conditions as in the photosensitive member of
Example 1 to form a protection layer.
Comparative Compound No. 10
##STR00023##
<Calculation of Energy Value of HOMO>
For the hole transporting compound used in Examples 1 to 18 and
Comparative Examples 1 to 8, the energy value of HOMO was
calculated by a density functional theory method (B3LYP/6-31G*).
The results are shown in Table 1.
TABLE-US-00001 TABLE 1 Used amount Hole Used amount (part) of
transporting (part) of compound compound hole Compound represented
HOMO Hole transporting transporting represented by by Formula value
compound compound Formula (2) (2) (eV) Example 1 Exemplary Compound
No. 1-1 4 -- -- -4.87 Example 2 Exemplary Compound No. 1-3 4 -- --
-4.89 Example 3 Exemplary Compound No. 1-7 4 -- -- -4.87 Example 4
Exemplary Compound No. 1-8 4 -- -- -4.84 Example 5 Exemplary
Compound No. 1-9 4 -- -- -4.86 Example 6 Exemplary Compound No.
1-15 4 -- -- -4.89 Example 7 Exemplary Compound No. 1-17 4 -- --
-4.81 Example 8 Exemplary Compound No. 1-18 4 -- -- -4.81 Example 9
Exemplary Compound No. 1-20 4 -- -- -4.86 Example 10 Exemplary
Compound No. 1-21 4 -- -- -4.86 Example 11 Exemplary Compound No.
1-26 4 -- -- -4.87 Example 12 Exemplary Compound No. 1-1 2.8
Exemplary 1.2 -4.87 Compound No. 2-1 Example 13 Exemplary Compound
No. 1-7 2.8 Exemplary 1.2 -4.87 Compound No. 2-1 Example 14
Exemplary Compound No. 1-7 2.4 Exemplary 1.6 -4.87 Compound No. 2-1
Example 15 Exemplary Compound No. 1-7 2 Exemplary 2 -4.87 Compound
No. 2-1 Example 16 Exemplary Compound No. 1-7 2.8 Exemplary 1.2
-4.87 Compound No. 2-3 Example 17 Exemplary Compound No. 1-7 2.8
Exemplary 1.2 -4.87 Compound No. 2-4 Example 18 Exemplary Compound
No. 1-7 2.8 Exemplary 1.2 -4.87 Compound No. 2-7 Comparative
Comparative Compound No. 1 4 -- -- -4.89 Example 1 Comparative
Comparative Compound No. 2 4 -- -- -4.88 Example 2 Comparative
Comparative Compound No. 3 4 -- -- -4.86 Example 3 Comparative
Comparative Compound No. 4 4 -- -- -5.05 Example 4 Comparative
Comparative Compound No. 5 4 -- -- -5.05 Example 5 Comparative
Comparative Compound No. 6 4 -- -- -5.02 Example 6 Comparative
Comparative Compound No. 7 4 -- -- -4.84 Example 7 Comparative
Comparative Compound No. 8 4 -- -- -4.71 Example 8 Comparative
Comparative Compound No. 9 4 -- -- -- Example 9 Comparative
Comparative Compound No. 10 1 -- -- -- Example 10
<Evaluation: Initial Sensitivity and Residual Potential>
The initial sensitivities and residual potentials of the
photosensitive member according to Examples 1 to 18 and Comparative
Examples 1 to 10 were evaluated under the following conditions.
First, under an environment of a temperature of 23.degree. C./50%
RH, the conditions of a charging device were set so that the
surface of the electrophotographic photosensitive member is -700 V,
using a photosensitive member test apparatus (product name: CYNTHIA
59, manufactured by GENTEC CO., LTD.). The potential of the
photosensitive member surface after a monochromatic light having a
light quantity of 20 (.mu.J/cm.sup.2) was irradiated to the surface
of the photosensitive member which was charged to -700 V was
measured, which was defined as a residual potential (-V). The
evaluation results are shown in Table 2.
<Evaluation: Smeared Image Evaluation Under High Temperature and
High Humidity Environment>
Smeared image evaluation was carried out under the following
conditions, using the photosensitive member according to Examples 1
to 18 and Comparative Examples 1 to 10.
As the electrophotographic apparatus, a modified copying machine of
a product name of iR-ADVC 5560, manufactured by Canon Inc., was
used. As the charging unit, a rubber roller type contact charging
capable of superimposing alternating current on direct current was
used. As the modification points, the machine was modified to allow
adjustment and measurement of image exposure laser power, an amount
of current flowing from the charging roller to the support of the
electrophotographic photosensitive member (hereinafter also
referred to as total current), and a voltage applied to the
charging roller. Further, the copying machine was used while a
heater and a cassette heater of the copying machine main body was
powered off.
First, the electrophotographic apparatus and the
electrophotographic photosensitive member were allowed to stand at
a temperature of 30.degree. C. and a humidity of 80% RH as the high
temperature and high humidity environment for 24 hours or more, and
then the electrophotographic photosensitive members of the Examples
and the Comparative Examples were mounted on a cyan cartridge of
the electrophotographic apparatus.
Next, as voltage applied to a charging roller, a direct current
component was set to -700 V, a frequency of the direct current
component was set to 1500 Hz, a potential between peaks Vpp was set
to from -400 V to -2000 V at 100 V intervals, and the total current
at each applied voltage was measured. Then, a graph with the
applied voltage on the horizontal axis and total current on the
vertical axis was created, and the applied voltage at which a
current amount deviated from the linear approximation curve at an
applied voltage from -400 V to -800 V (hereinafter also referred to
as a discharge current amount) was 100 .mu.A, was determined. The
total current was set to the total current value at the applied
voltage at which the discharge current amount was 100 .mu.A.
Next, the charge setting of the copying machine was set so that the
dark portion potential was -700 V. A solid image was output in a
cyan single color on A4 size plain paper, and the image exposure
light quantity was set such that an initial density on paper was
measured with a spectrodensity meter (product name: X-rite504,
manufactured by X-Rite Inc.) to be 1.45.+-.0.05.
A square grid image having an A4 size, a line width of 0.1 mm, and
a line interval of 10 mm was read from a scanner, and 5000 sheets
were continuously output in a cyan single color. After image
output, the main power of the electrophotographic apparatus was
turned off and left for three days. After being left, the main
power of the electrophotographic apparatus was turned on, and one
sheet of the square grid image was immediately identically output,
the smeared image of the output image was visually observed, and
the image flow 1 was evaluated based on the following criteria.
Evaluation rank was as follows.
Rank 6: the gird image was clearly output.
Rank 5: no abnormality was found in the gird image.
Rank 4: the horizontal line of the gird image was broken, but no
abnormality was found in the vertical line.
Rank 3: the horizontal line of the gird image has disappeared, but
no abnormality was found in the vertical line.
Rank 2: the horizontal line of the gird image has disappeared, but
the vertical line was not broken.
Rank 1: the horizontal line of the gird image has disappeared, and
the vertical line has also disappeared.
At this time, the horizontal line in the grid image refers to a
line parallel to a cylindrical axis direction of the photosensitive
member, and the vertical line refers to a line perpendicular to the
cylindrical axis direction of the photosensitive member. Each of
the evaluation results is shown in Table 2.
<Evaluation: Potential Fluctuation Evaluation During Repeated
Use Under Low Temperature and Low Humidity Environment>
The photosensitive members according to Examples 1 to 18 and
Comparative Examples 1 to 10 were used to evaluate the potential
fluctuations during repeated use of the photosensitive member under
the low temperature and low humidity environment under the
following conditions.
As the electrophotographic apparatus, a modified copying machine of
a product name of iR-ADVC 5560, manufactured by Canon Inc., was
used. As the modification points, the machine was modified to allow
adjustment of potential for charging the photosensitive member from
a charging roller and image exposure laser power. The
electrophotographic apparatus and the electrophotographic
photosensitive member were allowed to stand at a temperature of
15.degree. C. and a humidity of 10% RH as the low temperature and
low humidity environment for 48 hours or more, and then the
electrophotographic photosensitive member was mounted on a cyan
cartridge of the electrophotographic apparatus.
The surface potential of the electrophotographic photosensitive
member was measured by taking out a developing cartridge from the
evaluation apparatus, inserting a potential measurement device at
that position, and performing measurement. The potential
measurement device was configured to arrange a potential
measurement probe at a developing position of the developing
cartridge. The position of the potential measurement probe with
respect to the electrophotographic photosensitive member was at the
center in the axial direction of the cylindrical
electrophotographic photosensitive member, and the gap from the
surface of the electrophotographic photosensitive member was 3
mm.
The alternating current component of the charging roller was 1500
Vpp and 1500 Hz, an initial dart portion potential (VDa) was
adjusted to -700 V, an initial bright portion potential (VLa)
before endurance in image exposure by laser exposure irradiation
was adjusted to -200 V, and set values were recorded. The same
procedure was performed for each of the electrophotographic
photosensitive members for evaluating these operations.
A band image having an image density of 1% was printed, and 1000
sheets were continuously fed. After the end of endurance, a bright
portion potential (VLb) after 1000 sheets were fed was measured
promptly using the above-described potential measurement
device.
Then, a fluctuation amount between the initial bright portion
potential (VLa) before feeding papers and the bright portion
potential (VLb) after feeding papers was confirmed, which was
defined as a bright portion potential fluctuation .DELTA.VL(ab).
The results are shown in Table 2.
<Evaluation: Evaluation of Amount of Wear>
The photosensitive members according to Examples 1 to 18 and
Comparative Examples 1 to 10 were used to evaluate an amount of
wear of the surface layer during repeated use under the following
conditions.
As the electrophotographic apparatus, a modified copying machine of
a product name of iR-ADVC 5560, manufactured by Canon Inc., was
used. As the modification point, the machine was modified to allow
adjustment of image exposure laser power.
First, a film thickness of the surface layer at the initial stage
of each of the electrophotographic photosensitive members was
measured using an interference film thickness meter (product name:
MCPD-3700, manufactured by Otsuka Electronics Co., Ltd.).
Next, the electrophotographic apparatus and the electrophotographic
photosensitive member were allowed to stand at a temperature of
23.degree. C. and a humidity of 50% RH for 24 hours or more, and
then the electrophotographic photosensitive member was mounted on a
cyan cartridge of the electrophotographic apparatus. Initially, the
conditions of a charging device were set so that the surface of the
electrophotographic photosensitive member was -700 V. The image
exposure laser power was adjusted thereto and light amount setting
to lower the potential from -700 V to -200 V was recorded.
Next, a halftone image was output in a cyan single color on A4 size
plain paper, image exposure laser power was set such that a density
of the output image was 0.85 with a spectrodensity meter (product
name: X-rite504, manufactured by X-Rite Inc.), and 50000 sheets
were continuously output.
Next, the electrophotographic photosensitive member was taken out
of the electrophotographic apparatus, the film thickness of the
surface layer was measured after 50000 sheets output, and the
difference in the film thickness of the surface layer before and
after 50000 sheets output, that is, the amount of wear was
calculated. The above evaluation results are shown in Table 2.
TABLE-US-00002 TABLE 2 High temperature and Low temperature and
high humidity low humidity environment environment Residual
potential Evaluation of smeared Bright portion potential Amount of
wear (-V) image (V) (.mu.m) Example 1 39 4 5 0.4 Example 2 41 4 5
0.4 Example 3 40 5 6 0.4 Example 4 40 5 6 0.5 Example 5 45 5 7 0.4
Example 6 46 4 7 0.5 Example 7 53 4 7 0.6 Example 8 57 5 8 0.9
Example 9 48 5 7 0.5 Example 10 55 5 8 0.8 Example 11 60 5 14 0.9
Example 12 48 5 8 0.2 Example 13 50 6 10 0.3 Example 14 56 6 11 0.2
Example 15 65 6 13 0.2 Example 16 49 6 8 0.3 Example 17 49 6 8 0.3
Example 18 49 6 9 0.2 Comparative Example 1 71 1 33 0.6 Comparative
Example 2 43 2 8 0.4 Comparative Example 3 89 3 27 1.2 Comparative
Example 4 67 4 24 0.6 Comparative Example 5 68 4 21 0.5 Comparative
Example 6 70 3 35 0.8 Comparative Example 7 85 Not measurable Not
measurable Not measurable Comparative Example 8 73 3 17 1.4
Comparative Example 9 77 1 29 0.7 Comparative Example 10 70 1 32
0.9
In the Examples using the hole transporting compound according to
the present invention, the smeared image, the potential fluctuation
under the low temperature and low humidity environment, and the
wear resistance were able to be improved in a well-balanced
manner.
In Examples 12 to 18 using the compound represented by Formula (2),
the smeared image under the high temperature and high humidity
environment was more effectively suppressed, and the wear
resistance was excellent. In addition, the evaluation results of
the potential fluctuation under the low temperature and low
humidity environment were also excellent.
In Comparative Example 7 using Comparative Compound No. 7, the
polymerization reaction did not proceed well, and the repeated use
test was impossible.
While the present invention has been described with reference to
exemplary embodiments, it is to be understood that the invention is
not limited to the disclosed exemplary embodiments. The scope of
the following claims is to be accorded the broadest interpretation
so as to encompass all such modifications and equivalent structures
and functions.
This application claims the benefit of Japanese Patent Application
No. 2018-118897, filed Jun. 22, 2018, which is hereby incorporated
by reference wherein in its entirety.
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